Advective fluid motion due to traveling waves. (A) Illustration of particle paths over a cycle of vibration (not to scale). (B) An enlargement of a particle motion [the green curve in panel (A)] shows that a particle does not return to its original position, resulting in a drift velocity of 0.7 mm/s (actual value). (C–E) Advection of fluid. The red curves are fluid particle trajectories due to Stokes drift. The color contour represents the amplitude of the Stokes drift velocity. The results of three wave-speeds are shown (c = 80, 40 and 20 m/s).